EP3042210B1 - System and method for monitoring movements and vibrations of moving structures - Google Patents

Description

The invention relates to a system and a method for monitoring movements of a structure.

Movable structures, such as buildings or large machines, may e.g. environmental influences or own operating movements can result in movements or vibrations that can damage the structure or hinder its operation. In order to prevent damage, to plan a maintenance or to estimate a remaining life, such movements can be observed and monitored.

For monitoring of wind turbines known sensors, such as single-axis acceleration sensors with piezo technology, strain gauges, photometry or laser measuring systems are used. As a result, simple changes in position and frequency analyzes of structure-borne noise can be carried out, which enable detection of possible damage to parts of the system, for example on bearings, gear parts or rotor blades.

A disadvantage of this is that the measured values capture a movement of the system only uniaxial and only for selected measuring points.

The WO 2012/049492 A1 discloses a system for correcting navigation inertial data for navigation. The system uses information about buildings and / or other features in the environment to correct drift in the output of inertial sensors. In particular, the system uses the four outer walls of a building to determine the likely direction of movement of a user of the system located within the building. This information is used to correct the drift. The system includes a stochastic filter, in particular a Kalman filter, to process inertial data and make corrections to the inertial navigation data. The Kalman filter also allows integration of other navigation data, such as GPS data. The system can also use information from aerial images, such as maps and photographic data, using edge and line detection algorithms.

The US 2009/326851 A1 discloses an inertial measurement unit having a base with a plurality of physically separate sectors on each of which are arranged three sets of orthogonally oriented yaw rate sensors. Both three high-G orthogonally oriented acceleration sensors and three low-G orthogonally oriented acceleration sensors are also arranged on the base. A processor on the base includes software for receiving signals from the three sets of angular rate sensors and the three high-G and three low-G acceleration sensors. The software is also capable of calculating one or more of the following based on the received signals: a change in attitude, a change in position, a change in angular velocity, a velocity change, and a change in the acceleration of the instrument over a plurality of finite time increments ,

The WO 2013/110215 A1 discloses a method for determining the parameters of a wind turbine. Signals may be received from at least one micro-inertial measurement unit (mimu) mounted on or within a component of the wind turbine, and at least one parameter of the wind turbine may be determined based on the signals transmitted by the at least one mimu.

The DE 10 2006 005 258 A1 discloses a method for determining stresses of a mechanical structure and / or damage or states of the mechanical structure resulting from the stresses of the mechanical structure. For this purpose, rotations of a part of the mechanical structure caused by stresses / damages of the mechanical structure are measured via a fiber-optic rotation sensor, which is mechanically rigidly connected to the structural part, and from the measured rotations on the loads / damages / states of the mechanical structure.

"Condition monitoring and fault detection of wind turbines and related algorithms: A review" by Z. Hameed et al. (Renewable and sustainable energy reviews, Elsevier Science, New York, Vol. 13, No. 1, pp. 1-39 ) describes various techniques to monitor wind turbines and their performance.

The invention has for its object to provide a system and a method for monitoring movements of a structure, which allow an effective and secure monitoring of the structure and a basis for Provide repair, maintenance, and / or estimates of the remaining life of parts of the structure.

This object is achieved by a system according to claim 1 for monitoring movements of a structure and by a method for monitoring movements of a structure specified in an independent claim. Further developments can be found in the dependent claims.

A system for monitoring movements of a structure comprises at least one inertial measuring device attached to the structure for detecting rotational rates and acceleration values in the terrestrial inertial system. The system further comprises a central unit for determining a

Monitoring value based on the rotation rate and acceleration values by means of a navigation algorithm and an output unit for outputting the monitoring value.

The structure can be any object that can be put into motion and / or vibrations by external influences (environmental influences) or internal influences (operating behavior). It may, for example, be a building, such as a high-rise building or a transmission tower, or a machine, such as a construction machine, a crane or the like. Furthermore, it may also be structures that are built in the manner of a building and operated in the manner of a machine, such as a Ferris wheel, an oil rig or a wind turbine.

On the one hand, such structures can be set in motion by environmental influences, for example by the wind, the ocean current, the wave impact or movements of the earth's surface, e.g. in an earthquake. On the other hand, such structures can also be set in motion by their own operating movements, for example by working movements of a part of the structure, drive or transmission vibrations. In addition, there may be interactions between environmental influences and internal movements of the structure that lead to complex movement behavior.

Such movement and vibration can damage the structure and cause fatigue, such as fatigue cracking or breakage. You can continue to influence the operating behavior of the structure while restricting its use or operating efficiency.

Furthermore, it is also possible that the structure changes over time, for example due to aging, wear, structural damage, mechanical damage or environmental influences. For example, in complex moving structures such as wind turbines to ice accumulation or water retention in the rotor blades come. Stress and fatigue can cause material properties to change, parts of the structure to soften or crack. Such changes in the structure are reflected in the motion behavior of the structure. For example, this can change frequencies or amplitudes of oscillations or movements. The changes can be detected on the basis of the rotational rates and acceleration values measured by the inertial measuring device. This makes it possible to identify the need for action, for example Recognize maintenance, servicing or operation and implement such measures before significant damage occurs.

Monitoring of movements of the structure is thus required both for reasons of operational safety and operating efficiency.

To monitor the movements, one or more inertial measuring devices can be fastened to the structure or a part of the structure, which make it possible to detect the rotation rates and acceleration values occurring at the fastening points with respect to the earth-tight inertial system. For this purpose, systems with inertial sensors (acceleration and angular rate sensors) of the types MEMS (microelectromechanical systems) and / or FOG IMU (inertial measuring units with fiber gyros) may be used.

The acquired acceleration values and rotation rates can be transmitted to the central unit, for example via a wireless or wired network for uni- or bidirectional communication.

In the central unit, speeds and angular velocities and an orientation and a position of the inertial measuring device in space can be determined on the basis of the measured rotation rates and acceleration values by means of a navigation algorithm, for example by means of continuous integration or summation of the measured rotation rates and accelerations.

In this case, classical navigation algorithms can be used, as are known, for example, from the field of vehicle, ship and / or flight navigation, e.g. with a Schuler compensation of the detected rotation rates and accelerations.

On the basis of the measured rotation rates and acceleration values, the calculated (angular) velocities, the orientation and / or the position, movements of the structure can be detected and monitored. In particular, the movements, vibrations and deflections present at the measuring points can be determined.

Furthermore, the monitoring value can be determined on this basis. The monitoring value can be, for example, the measured yaw rate, the measured acceleration value, the calculated (angular) speed, orientation and / or position, or a further value determined therefrom, such as a movement frequency and / or amplitude, a torsion and / or a deflection.

The monitor value may be communicated to the output unit by wireless or wired communication. In the simplest case, the output unit may comprise a screen with output of the monitoring value or its course, but also other components, such as a data memory for collecting and documenting the course of the monitoring value over time. Alternatively or additionally, the output unit may have a complex warning and alarm system.

In addition, it is possible to couple the output unit in the manner of a control system with actuators of the structure. In this case, depending on the monitoring value, control information, for example manipulated variables, can be transmitted to the actuators. In the case of monitoring a wind energy plant, it is possible, for example, to regulate a position of the rotor blades in dependence on a monitoring value, which allows conclusions about a deflection of the rotor blades, in order to avoid excessive loading of the rotor blades.

On the basis of the monitoring value and other monitoring information, it is possible to draw conclusions about movements and vibrations of the structure and thus, for example, draw conclusions about possible malfunctions, fatigue or damage. This allows, for example, an estimate of the remaining service life of the structure or its components and can be used as a basis for maintenance planning. Such estimates are particularly helpful in monitoring structures with poor accessibility (e.g., offshore wind turbines) and high capacity machines (presses of a large-scale mill), where high costly maintenance is required. Furthermore, such characteristics are important in terms of safety requirements, as the continuous monitoring is regularly documented and maintenance is promptly displayed.

In one embodiment, the inertial measuring device has three yaw rate sensors each having detection axes that are linearly independent of one another and / or mutually orthogonal and three acceleration sensors each having mutually linearly independent and / or mutually orthogonal detection directions.

For example, the rotation rate sensors may have three mutually orthogonal detection axes x, y and z, which correspond to the detection directions of the acceleration sensors. With the help of the rotation rate sensors (the gyroscopic sensors) the rotational movement can be calculated, while with the help of the acceleration sensors (the translation sensors) the translatory movement can be calculated. Consequently, any movements of the inertial measuring device can be determined according to the six degrees of freedom.

In one embodiment, the central unit is designed to determine and / or correct a measurement error of the inertial measuring device on the basis of a boundary condition predetermined by the structure.

In particular, the classical inertial navigation, starting from a predetermined starting position, is subject to a continuous increase in the orientation or position error resulting from the "integration" or accumulation of any errors or measurement inaccuracies (eg zero error) of the inertial sensors (yaw rate and acceleration sensors ). This growth is called drift.

In order to restrict or compensate for drifting of the position and position and thus also of the monitoring value, stable conditions and conditions that are present on the structure can be taken into account when using the navigation algorithm. These conditions can be recorded, for example, in the form of boundary conditions of the navigation. Consequently, the navigation algorithm can be supported by these conditions and conditions. An error in the calculation result or an error of the monitoring value can be estimated and / or compensated on this basis.

The consideration of boundary conditions can in the simplest case include a comparison of the boundary condition (eg a known geographic location of the structure) with calculated values (velocity, angular velocity, position and orientation). On this basis, the error (eg zero error) of the inertial measuring device (rotation rate and acceleration sensors) can be estimated and the accuracy of the measurement continuously improved. The consideration of, for example, several or complex boundary conditions can be realized by means of a Kalman filter in the navigation algorithm.

In a further embodiment, the central processing unit may be configured to determine the boundary conditions on the basis of at least one information from a group comprising a substantially stationary position of the structure, a position of at least part of the structure determined on the basis of a satellite-supported position signal Constraining a degree of freedom of movement of at least a portion of the structure, an inclination angle of at least a portion of the structure, an average value (eg, predetermined or derived from measured values or calculated values) of movement of at least a portion of the structure and / or the inertial measuring device, and one of Structure acting wind speed, wind direction, flow velocity, flow direction and / or Wellenaufschlagrichtung.

Consequently, the conditions of the structure and its location in the environment as well as any knowledge about environmental conditions can be used to support the navigation algorithm or to estimate the position and location drift.

Such boundary conditions are not known from classic vehicle navigation, since they are generally not available on vehicles. They are therefore not used in the context of classic vehicle navigation for error correction or drift prevention. However, in the monitoring of moving structures, which may for example be arranged stationary, such conditions may exist and be used for error correction.

An error estimation and error correction improved by the boundary conditions makes it possible to specify or calculate the determined values with a higher accuracy, or alternatively to use less expensive, more drift-prone inertial measuring devices, since the errors that occur are estimable and correctable.

In particular, buildings and / or large-scale facilities such as wind turbines and oil rigs are often stationary, ie placed at a fixed point in the terrestrial inertial system. For these systems it is possible to support the navigation algorithm by the boundary conditions.

A corresponding support is also possible in non-stationary structures, if a position signal can be used to determine the position of the structure. For example, a Global Navigation Satellite System (GNSS) receiver may be used to receive and evaluate a satellite-based position-finding signal, e.g. a GPS, GLONASS, Compass or Galileo receiver. Alternatively, another, for example, local positioning optical position signal may be used, or an optical recognition method that analyzes an image captured by a camera. The position thus determined may be used to detect and correct drift of the sensors, an error in the calculated position and orientation values, or a systematic error in the monitoring value.

The boundary condition may also be predetermined by a restriction of a degree of freedom of movement of at least part of the structure. For example, during a rotation and / or oscillation of a rotor blade, a position along the rotor blade and thus, for example, a distance of a point to the hub will hardly change. Consequently, movements of this point by the fixation of the rotor blade to the hub are subject to a restriction of the degree of freedom. This restriction can be used as a boundary condition, for example to detect or correct a systematic measurement error of the sensors.

Furthermore, an angle of inclination of at least part of the structure can also be determined as a boundary condition. For example, an inclination of a tower of a wind turbine can lead to the displacement of the position of an inertial measuring device arranged in a nacelle of the wind turbine. If only the known stationary position of the structure is detected to support the navigation algorithm, then the translational movement of the inertial measuring device is optionally designed as a position drift and a possibly critical inclination of the tower is not recognized. However, taking into account the inclination angle, position drift and inclination can be detected and separately monitored or corrected.

Furthermore, the boundary condition may be determined based on an average value of a movement of at least a portion of the structure and / or the inertial measurement device. For example, it is possible for the part of the structure to which the inertial measuring device is attached to be vibrated, for example by wind load or wave impact. The vibrations change the Position of the internal measuring device and are recognized as acceleration. In order nevertheless to be able to detect a zero error or a systematic drift of the inertial measuring device, an average value of the movement over a predetermined period of time can be determined and used as a boundary condition for determining and correcting the measurement error, for example based on a Kalman filter.

Furthermore, the boundary condition can also be determined on the basis of an environmental influence acting on the structure. In particular, environmental influences such as, for example, a wind speed, a wind direction, a flow velocity, a flow direction and / or a shaft impact direction, for example in offshore wind energy plants or oil rigs, can lead to movements and / or vibrations of the wind energy plant or oil rig, which are measured by the inertial measuring device attached thereto. Such environmental influences therefore affect the position and orientation determination of the structure and can be confused with a zero-point error, that is to say a systematic drift of the inertial measuring device. However, if the boundary condition determined on the basis of the environmental influences is taken into account in the context of the error correction, an error correction is just as possible as a recognition of the displacement of the position or orientation of the inertial measuring device.

In another embodiment, the system includes a plurality of inertial measurement devices attached to the structure, wherein the central unit is configured to determine the monitoring value based on a relative movement between each two of the plurality of inertial measurement devices.

By using a plurality of inertial measuring devices, it is possible to measure movements or vibrations of the structure at several measuring points (mounting locations of the inertial sensors). As a result, an accurate detection of relative movements within the structure is possible, which allows conclusions on deflections, torsions and / or deflections between the measuring points. Such movements have a direct impact on the material and thus provide important information for monitoring, determining service intervals and / or lifetime estimation.

In one variant, the structure may comprise a plurality of components coupled to one another, wherein in each case an inertial measuring device is arranged on at least two of the components.

The arrangement of the inertial measuring devices on a plurality of components makes it possible to monitor relative movements of the components relative to one another, whereby the movement of the components relative to one another and thus, for example, a loading of the coupling devices between the components becomes detectable.

For example, several inertial measuring devices can be used to monitor a wind turbine with a tower, a nacelle disposed on the tower, and a rotor mounted on the nacelle with rotor blades for driving a generator.

When using a plurality of arranged on a rotor blade inertial measuring devices, for example, a deflection of the rotor blade can be detected. On this basis, a warning message generated and / or a position of the rotor blade in the wind can be actively controlled. This makes it possible to detect and / or prevent damage.

Furthermore, an orientation of the inertial measuring device attached to the nacelle with respect to the inertial measuring device attached to the tower can be determined. On this basis, for example, taking into account a detected wind direction, the nacelle orientation can be assessed or corrected.

The use of multiple inertial measuring devices on the structure or on different parts of the structure thus makes it possible to detect and evaluate movements of the structure in higher modes and to effectively monitor the structure.

In a further variant, the structure is a wind energy plant, and the inertial measuring device is arranged on a rotor blade of the wind energy plant. In this case, the inertial measuring device can be arranged such that a tangent of a rotation path of the inertial measuring device to none of the detection directions of the rotation rate sensors is perpendicular and / or parallel (schiefachsige / oblique-angled mounting). Additionally or alternatively, the central processing unit may be configured to determine the boundary condition on the basis of at least one information from the group: the acceleration of gravity acting cyclically on the inertial measuring device with one revolution of the rotor, which is cyclic with one revolution of the rotor to the inertial one Measuring device acting earth rotation and an output signal of a rotary encoder of the rotor.

The oblique mounting of the sensors on the rotor blade ensures that the detection axes or directions are not arranged collinear to a rotational tangent of the rotor blade. Consequently, all measuring axes are equally exposed to acceleration or rotation during one revolution of the rotor blade.

As a result of the arrangement of the inertial measuring device on the rotor blade, the inertial measuring device is set in rotation with the rotor blade during operation of the wind energy plant. Here, the gravitational acceleration of +/- 1 g acts cyclically with the rotation of the rotor on the inertial measuring device. Likewise, the earth rotation also acts cyclically with the rotation of the rotor on the inertial measuring device. These effects are reflected in the accelerations and rotation rates detected by the inertial measuring device and thus in the output signal of the inertial measuring device.

The acceleration and rotation of the earth cyclically acting on the rotor revolutions superimpose the output signal and can be detected and compensated in the output signal. In particular, it can be used as a boundary condition of the above-described error correction. This makes it possible to detect, estimate or compensate for systematic errors of the inertial measuring device, in particular a gyroscope factor error of the inertial measuring device. Thereby, an increase of the errors by the gyroscope factor error can be prevented.

Such an error correction can also be used in particular when calibrating the sensors. The slippery mounting of the inertial measuring device on the rotor blade makes it possible to calibrate all measuring axes or the associated sensors in this way.

Alternatively or additionally, the output signal of a rotary pulse generator of the rotor can be used to detect the rotation of the rotor and on this basis to assess the effect of gravitational acceleration or Erdrotation on the measurement result and to calibrate the inertial measuring device.

In another embodiment, the structure is also a wind turbine. The inertial measuring device is arranged on a nacelle of the wind turbine. Furthermore, the central unit is designed to determine the boundary condition on the basis of a rotation angle sensor of the nacelle.

For example, the rotary encoder can be installed at the coupling point from the tower to the nacelle. The output signal of the rotary encoder can be compared with an output signal of the inertial measuring device and used as a boundary condition for error estimation or calibration of the inertial measuring device. As a result, a gyroscopic factor of the inertial measuring device can be detected or corrected. Subsequently, an orientation of the nacelle in the azimuth direction can be detected and adapted, for example, with regard to a wind direction. This allows optimal use of wind energy.

In another embodiment, the central processing unit is configured to determine the guard value based on at least one information from the group comprising: an output value of a structural model of the structure, structural status information, environmental parameter, yaw rate, acceleration, angular velocity, velocity , an orientation and / or a position at a point of the structure different from an installation location of the inertial measuring device, a movement amplitude and / or a movement frequency of a vibration of the structure and a torsion between two different points of the structure.

In particular, it is possible to feed the acceleration and rotation rate values measured by the inertial measuring device or the inertial measuring devices, for example, into a mathematical model that is based on finite elements and maps the physical conditions of the structure, which can be stored in a memory. For example, the central unit can feed in the measured values by accessing the memory and successively calculate a dynamic behavior of the structure on the basis of the measured values. This stimulates the computer model and simulates the dynamic behavior (movements, vibrations) of the structure.

Alternatively or additionally, status information of the structure, such as an operating parameter such as a gearbox setting and / or a generated energy of a wind turbine, can be used in the determination of the monitoring value. This information can also be fed into the computational model of the structure or compared with the simulated dynamic behavior of the computational model. You can do that on the one hand to stimulate, on the other hand be used to validate the computational model.

As environmental parameters for determining the monitoring value, for example (satellite-based) position signals with respect to the position of at least a part of the structure, a nacelle orientation, a rotation angle of the rotor, a pitch of the rotor blades, a wind direction and wind force, a wave direction and wave strength, a flow, a temperature and a power output, for example, a wind turbine to be considered. For example, information relating to a measured wind direction can be used to evaluate or correct an orientation of the nacelle in the azimuth direction.

Furthermore, the central unit can be designed to determine movements at a different point of the structure from the installation location of the inertial measuring device. This can be accomplished by injecting three-dimensional yaw rates and accelerations into the computational model, where yaw rates and accelerations were measured from one or more inertial measurement devices with other locations other than the point. On this basis, movements can also be calculated at other points of the structure. For example, torsions between two different points of the structure, e.g. between two different points of a rotor blade or tower, and thus mechanical loads on the structure are detected. So movements with higher modes can be determined or calculated. This allows effective modeling and monitoring of movements and vibrations of the forest.

Furthermore, the monitoring value can be determined on the basis of a movement amplitude and / or a movement frequency of a vibration of the structure. In particular, due to the measured, for example three-dimensional acceleration values, vibrations of the structure or its parts and thus the structure-borne noise of the structure can be detected. This makes it possible to detect mechanical damage to the structure, for example on the drive train of a wind turbine (for example fractures and wear on the gear, on the teeth and / or in the bearings, which lead to a change in structure-borne noise).

With the help of a structure-borne sound analysis based on arranged on the rotor blades inertial measuring devices, for example, ice and Cracks on the rotor blades are detected and appropriate maintenance measures are initiated.

In a further variant, the central unit can be designed to detect limit values of the monitoring value and to send information to the output unit when at least one of the limit values is exceeded. It can also be designed to send a proposal for manipulated variables for setting actuators on the structure to the output unit on the basis of the monitoring value. Alternatively or additionally, the central unit can be designed to send the manipulated variables to the actuators on the basis of the monitoring value.

This variant enables a wide range of monitoring options, from limit monitoring and overflow reporting to the determination of control suggestions, to active regulation of the dynamic behavior of the structure.

Thus, threatening damage can be detected and reported. As part of the maintenance of wind turbines, the detection and reporting of ice use, imbalances of the rotor or transmission damage enables safe operation and detection of control and maintenance requirements.

Furthermore, the maintenance personnel can be supported by the outputs on the output unit, for example, by proposals for controlling the wind turbine are generated. For example, a change in the position of the rotor blades or a change in a transmission setting can be proposed. As a result, damage can be avoided and better utilization can be achieved.

In addition, in addition to the output of the monitoring value, the central unit can transmit manipulated variables to the actuators of the structure. This makes it possible to react quickly to a critical state detected on the basis of the monitoring value and to turn the rotor blades quickly and actively out of the wind, for example after a gearbox damage. Furthermore, a need-based and at the same time material-saving control of the power output can be realized.

Depending on a criticality level of the particular monitoring value, the transmission of the manipulated variables to the actuators can be made dependent, for example, on a human confirmation by the maintenance personnel.

A method for monitoring movements of a structure comprises detecting rotation rates and acceleration values in the inertial inertial system of at least one inertial measurement device attached to the structure, determining a monitoring value based on the rotation rates and acceleration values by means of a navigation algorithm, and outputting the monitoring value.

For example, the method may be practiced in any embodiment of the system described above.

In one variant, the method may include injecting the yaw rates and acceleration values into the computational model of the structure, validating the computational model based on a comparison of the course of the measured yaw rates and acceleration values, each with yaw rates and acceleration values calculated in the model, and determining the guard value based on the computational model exhibit.

This method makes it possible, for example, to stimulate the calculation model by the measured values and, based on the stimulation, to calculate the dynamic behavior of the model, for example stepwise over a predetermined period of time. In parallel, measured values of the acceleration and rotation rate sensors of the inertial measuring device (s) can be detected over the corresponding period of time. The calculation model can be validated by a comparison of the detected and calculated rotation rates, or the angular velocity, orientation or position calculated or calculable on this basis.

For example, the calculation model can be considered suitable if deviations are present only below a predetermined limit. Otherwise, a need for an adaptation of the calculation model or the calculation method can be detected. Based on the validated calculation model, the monitoring value can be determined and output.

In a further variant of the method, the structure may comprise at least a part of a wind energy plant with a rotor with rotor blades, wherein the inertial measuring device is arranged on one of the rotor blades. The method may include calibrating the inertial measuring device based on a cyclic one-revolution of the rotor acting on the inertial measuring device Acceleration due to gravity, on the basis of an earth rotation which acts cyclically on one revolution of the rotor on the inertial measuring device and / or on the basis of a rotary encoder of the rotor (as described above).

During the oblique mounting of the inertial measuring device (s) on one of the rotor blades, the zero point error and the gyro scale factor of the inertial measuring device can be estimated and corrected within the scope of a calibration. This method can be helpful in particular when commissioning the wind energy plant.

In a further variant, the structure comprises at least a part of a wind power plant with a rotor with rotor blades, wherein the inertial measuring device is arranged on the rotor. The method includes detecting an imbalance of the rotor based on the detected rotation rates and acceleration values.

This method can be used in particular when balancing the rotor. Imbalances can be detected and corrected, which makes effective and fatigue-free operation of the wind turbine possible.

Fig. 1

ein System zur Überwachung einer Windenergieanlage auf Basis von Messergebnissen mehrerer inertialer Messvorrichtungen unter Nutzung eines Navigationsalgorithmus, und

Fig. 2

ein Blockdiagramm eines Systems zur Überwachung einer Windenergieanlage auf Basis eines Rechenmodells.

These and further features of the invention are explained in more detail below by means of examples with the aid of the accompanying figures. Show it:

Fig. 1

a system for monitoring a wind turbine on the basis of measurement results of several inertial measuring devices using a navigation algorithm, and

Fig. 2

a block diagram of a system for monitoring a wind turbine based on a computer model.

Fig. 1 shows a system for monitoring movements of a structure serving as wind turbine 1.

The wind energy installation 1 has a tower 2 erected on a subsoil, on which a nacelle 3 with a rotor 4 provided thereon with rotor blades 4a, 4b and 4c is arranged. At the wind turbine 1 or its components 2, 3, 4, 4a, 4b and 4c, respectively one or more inertial measuring devices 5 are arranged. These are in the drawing by small Box shown and for reasons of clarity not individually denoted by reference numerals.

The inertial measuring devices 5 each have three rotation rate sensors with mutually linearly independent and / or mutually orthogonal detection axes as well as three acceleration sensors each having linearly independent and / or mutually orthogonal detection directions. Its output signal can be used to determine a calculation of angular velocities and speeds or orientations and positions of the respective inertial measuring devices 5 in the terrestrial inertial system with the aid of a navigation algorithm known for example from vehicle, ship or flight navigation.

As a basis for such calculations, a transmitting unit 6 collects the values measured by the inertial measuring devices 5, as well as environmental parameters and status information of the wind energy plant optionally measured by a further sensor unit 7. The environmental parameters may, for example, relate to a wind direction, a wind force, a temperature, a wave direction and / or wave strength (for example in the case of offshore installations). The status information may relate to a status of the wind turbine comprising, for example, an orientation of the nacelle 3, a rotation angle of the rotor 4, a pitch of the rotor blades 4a, 4b, 4c, and a power output of the generated energy. Furthermore, the status information can also include a position signal received, for example, from a satellite 8, which can be detected by the sensor unit 7 and transmitted to the transmitting unit 6.

The collected data can be sent from the transmitting unit 6, for example by means of wireless or wired communication, to a receiver 9 of a monitoring device 10. The monitoring device 10 may be located locally in an environment of the wind turbine 1, but also remote from the wind turbine 1. A local arrangement of the monitoring device 10 may also mean an arrangement within or on the wind turbine 1 or an arrangement in a close environment. For example, the monitoring device 10 may be arranged in a monitoring and control center of a wind farm, in which the wind turbine 1 is set up. An arrangement away from the wind turbine 1 is useful, for example, in offshore wind turbines.

The monitoring device 10 may have a central unit 11 for determining the monitoring value on the basis of the transmitted data, in particular based on the rotational rates and acceleration values measured by the inertial measuring devices 5. For example, the CPU 11 may perform a classic navigation algorithm with Schuler compensation.

Thereby, an angular velocity and velocity of a movement and a position and orientation in space can be determined for each of the inertial measuring devices. Furthermore, relative movements of the inertial measuring devices can be determined and evaluated to each other. On this basis, a monitoring value can be determined, for example a pitch of a rotor blade 4c or a torsion of the tower 2 by wind load.

The monitoring value can be sent to an output unit 12, which makes the monitoring value accessible to, for example, an operator. Alternatively, the monitoring value can also be recorded in a memory 13 and stored for documentation purposes.

When using classical navigation algorithms for monitoring the movement of structures, it is possible to include conditions and conditions resulting from physical properties of the structure in the navigation algorithm, and in particular in error estimation or error correction.

In particular, the measured values of the inertial measuring devices 5 are typically overlaid with errors that are due, for example, to a zero error or scale factor error of the included acceleration and yaw rate sensors. When determining the directional and angular velocities or the position and the orientation, the errors are integrated and lead to a continuous drift.

In the monitoring of structures, spatial conditions of the structure can be considered as boundary conditions of the navigation algorithm and taken into account in the context of the error correction, for example by means of a Kalman filter. Such boundary conditions are, for example, a (geographical) position of the structure which is generally fixed in buildings or on fixed foundations. In the case of offshore installations, the position can be determined, for example, by a satellite-supported position signal (GPS). Further boundary conditions can, as described above, also determined from environmental information or by other sensors, such as a tower tilt sensor, are determined.

The boundary conditions make it possible to estimate and correct the systematic errors in the measured values of the inertial measuring devices. This makes possible an accurate position and orientation determination that provides a suitable basis for determining the guard value. Further boundary conditions that can lead to an improvement of the error estimation and error correction have already been described above in the general part and can be found in the in Fig. 1 shown embodiment can be used.

Furthermore, the central unit 11 of the monitoring device 10 can be designed to detect limit values of the monitoring value and to send information to the output unit 12 when at least one of the limit values is exceeded. The specification of limit values enables the detection and reporting of imminent damage as well as maintenance and control requirements.

The central unit 11 may also suggest a suggestion for manipulated variables for setting actuators on the wind energy plant 1 on the basis of the monitoring value. Such suggestions can be displayed to the operating personnel, for example at the output unit 12. For example, they may include aligning the nacelle 3 according to a detected wind direction, aligning the rotor blades with regard to a power to be generated, and / or shutting down the wind turbine, for example in the case of imminent damage or in the event of damage.

Furthermore, the central unit 11 can transmit the manipulated variables via a transmitting unit 14 to a receiving unit 15 of the wind energy plant 1. In the wind energy plant 1, the received manipulated variables can be used to correspondingly control actuators of the wind power plant and, for example, to initiate a turning of the nacelle 3 or an alignment of the rotor blades 4a, 4b, 4c.

Furthermore, the central unit 11 can determine the monitoring value, for example, on the basis of a computer model which can calculate a dynamic behavior of the wind energy plant 1 and can be stored, for example, in the memory 13. The rotational rates and accelerations measured by the inertial measuring devices 5 or the speeds, angular speeds, determined therefrom, Positions and orientations can be fed into the calculation model, which calculates, simulates or dynamically maps the dynamic behavior of the wind turbine on this basis.

The further data measured by the sensor unit 7 and transmitted by the transmitting unit 6, such as environmental parameters and status information, can also be used to stimulate the model.

The calculated dynamic behavior can be checked and evaluated against the background of further measured values of the inertial measuring devices 5 or further status information, so that these values simultaneously enable stimulation and support of the computer model.

The calculation model can be used, for example, to detect and evaluate movements with higher modes of the wind turbine 1, such as, for example, torsions of the tower 2 or deflections of the rotor blades 4a, 4b, 4c.

A degree of detail of the calculation steps of the calculation model can be determined with regard to the required computational accuracy and the available computing power. As far as the monitoring device 10 and in particular the central unit 11 has sufficient computing capacity, the calculation and evaluation can be carried out essentially under real-time conditions or with only a slight delay.

In operational operation, the system for monitoring the wind turbine or the monitoring method implemented therein can be used as condition monitoring system by comparing the determined movements, vibrations, frequencies and / or amplitudes with predetermined limits. As part of condition monitoring, warnings can be issued when the limit values are exceeded.

Furthermore, the measured and calculated values can also be regarded as controlled variables in order to enable an optimal setting of the wind turbine 1 on the one hand with regard to the acting forces and on the other hand with regard to the power to be delivered. This allows good utilization in simultaneous material-saving operation.

An evaluation of load changes and different loads over a longer period of time allows the determination of a residual life of the Wind turbine 1 or its components, and / or the planning of maintenance activities.

As already described above, the measurement and calculation values can also be used in the development and testing of plants and in their commissioning, for example to detect and correct excessive loads or imbalances.

Fig. 2 shows a block diagram of one embodiment of a monitoring system, for example, the monitoring system Fig. 1 ,

The upper section describes the sensors and their arrangement. Accordingly, the tower 2, the nacelle 3 and the rotor blades 4a, 4b, 4c each have n inertial measurement units (IMU), which are each fastened to different positions of the respective component.

The inertial measuring devices 5 transmit their data in the middle region of the Fig. 2 illustrated navigation units of the respective components in which the navigation calculations are performed on the basis of the navigation algorithm. Here, for example, the speeds, angular velocities, positions and orientations of the inertial measuring devices can be determined. The navigation is supported in each case by suitable additional data or boundary conditions of the structure, for example by a GPS signal, a nacelle orientation, a rotation angle of the rotor and / or a pitch of the rotor blades. As described above, this information can be used, for example, for error estimation, error correction and / or sensor calibration.

At the bottom of the Fig. 2 the model-based filtering of the data is shown, in which the results of the navigation calculations and other environmental parameters (wind direction, wind force, temperature, wave direction, wave strength) and status information (nacelle direction, rotor rotation angle, rotor blade pitch, power output) of the wind turbine 1 are fed with. The data can be processed continuously and essentially in real time. The model-based filtering can consequently correspond to a simulation which enables a model-supported evaluation of the data "on-line", ie without time delay, for example according to possibly given real-time requirements.

As part of the model-based filtering, a calculation model of the wind turbine is used to calculate the dynamic behavior of the wind turbine 1. As described above, the navigation data may stimulate, support, and validate the model. As output, the model-based filtering provides information for example on the state of movement of selected positions, warnings if predefined limit values are exceeded and / or service life parameters. These results can be sent, for example, to the output unit 12 in order to make them accessible to the operating personnel, in the context of condition monitoring, maintenance planning and / or as part of an active control of the wind energy plant 1.

Consequently, the use of inertial measurement systems and classical navigation algorithms in the field of building and plant monitoring can enable effective monitoring and control of the respective structure. The boundary conditions that apply to such buildings and installations can be used to estimate and compensate for the errors (zero point and scale factor error) that typically occur in the context of inertial navigation. On this basis, on the one hand, effective, on the other hand plant-saving operation of, for example, wind turbines and cost-optimized maintenance planning can be achieved.

Claims (12)

1. System for monitoring of movements of a stationary structure (1) comprising:

   - at least one inertial measurement device (5) mounted to the structure for determining of rotation rates and acceleration values in a earth fixed reference system,

   - a central unit (11) for determining a monitoring value on the basis of the rotation rates and acceleration values by means of an inertial navigation algorithm, and

   - an output unit (12) for outputting of the monitoring value, wherein

   the central unit (11) is configured to determine and/or correct a measurement error of the inertial measurement device (5) on the basis of a boundary condition predetermined by the structure in order to support the navigation algorithm, and

   - the central unit (11) is configured to determine the boundary conditions on the basis of at least one information of a group comprising

   + a substantially stationary position of the structure (1),

   + a constraint of a degree of freedom of a movement of at least a part of the structure (1),

   + an inclination angle of at least a part of the structure (1),

   + a mean value of a movement of at least a part of the structure (1) and/or of the inertial measurement device (5).
2. System according to claim 1, wherein

   - the inertial measurement device (5) comprises three rotation rate sensors having detection axes that are each linearly independent of each other and/or orthogonal to each other as well as three acceleration sensors having detecting directions that are each linearly independent from each other and/or orthogonal to each other.
3. System according to one of the preceding claims, having

   - several inertial measurement devices (5) mounted to the structure, wherein

   - the central unit (11) is configured to determine the monitoring value on the basis of a relative movement between at least any two of the several inertial measurement devices (5).
4. System according to one of the preceding claims, wherein

   - the structure (1) comprises several components (2, 3, 4, 4a, 4b, 4c) that are coupled to each other, and wherein

   - one inertial measurement device is mounted on at least two of the components (2, 3, 4, 4a, 4b, 4c), respectively.
5. System according to one of the preceding claims, wherein

   - the structure is a wind turbine (1) and the inertial measurement device (5) is arranged on a rotor blade (4a, 4b, 4c) of the wind turbine (1), wherein

   - the inertial measurement device (5) is arranged such that a tangent of a path of rotation of the inertial measurement device (5) is not perpendicular and/or parallel to any of the detecting directions of the rotation rate sensors, and/or

   - the central unit (11) is configured to determine the boundary conditions on the basis of at least one information of the group comprising

   + gravity acceleration acting cyclically during a revolution of the rotor (4) onto the inertial measurement device (5),

   + the rotation of the earth acting cyclically during a revolution of the rotor (4) onto the inertial measurement device (5), and

   + an output signal of a rotary pulse generator of the rotor (4).
6. System according to one of the preceding claims, wherein

   - the structure is a wind turbine (1) and the inertial measurement device is arranged on a housing (3) of the wind turbine (1), and

   - the central unit (11) is configured to determine the boundary condition on the basis of a rotary encoder of the housing (3).
7. System according to one of the preceding claims, wherein

   - the central unit (11) is configured to determine the monitoring value on the basis of at least one information of the group comprising

   + an output value of a mathematical model of the structure (1),

   + a status information of the structure (1),

   + an environmental parameter,

   + a rotation rate, an acceleration, an angular velocity, a velocity, an orientation, and/or a position of a location of the structure different from an installation location of the inertial measurement device (5),

   + a torsion between two different locations of the structure, and

   + an amplitude and/or frequency of movement of an oscillation of the structure.
8. System according to one of the preceding claims, wherein

   - the central unit (11) is configured to

   + capture threshold values of the monitoring value and to send information to the output unit (12), if at least one of the threshold values is exceeded,

   + send on the basis of the monitoring value a proposal for actuating variables for adjusting of actuators of the structure (1) to the output unit (12), and/or

   + send on the basis of the monitoring value the actuation variables to the actuators.
9. Method for monitoring of movements of a stationary structure (1) comprising:

   - determining of rotation rates and acceleration values in an earth fixed reference system of at least one inertial measurement device (5) mounted to the structure (1),

   - determining of a monitoring value on the basis of the rotation rates and acceleration values by means of an inertial navigation algorithm,

   - determining and/or correcting a measurement error of the determined rotation rates and acceleration values on the basis of a boundary condition predetermined by the structure (1)

   - outputting of the monitoring value, wherein
   a measurement error of the inertial measurement device (5) is determined and/or corrected on the basis of a boundary condition predetermined by the structure and thus the navigation algorithm is supported, and
   the boundary condition is determined on the basis of at least one information of a group comprising

   + a substantially stationary position of the structure (1),

   + a constraint of a degree of freedom of a movement of at least a part of the structure (1),

   + an inclination angle of at least a part of the structure (1),

   + a mean value of a movement of at least a part of the structure (1) and/or of the inertial measurement device (5).
10. Method according to claim 9, comprising:

    - inputting of rotation rates and acceleration values into a mathematical model of the structure,

    - validating of the mathematical model based on a comparison of the evolution of the measured rotation rates and acceleration values with rotation rates and acceleration values, respectively, that are calculated with the model, and

    - determining the monitoring value on the basis of the mathematical model.
11. Method according to claim 9 or 10, wherein
    the structure comprises at least a part of a wind turbine (1) having a rotor (4) with rotor blades (4a, 4b, 4c), and wherein the inertial measurement device (5) is arranged on one of the rotor blades (4a, 4b, 4c), comprising:

    - calibrating the inertial measurement device (5) on the basis of gravity acceleration that acts cyclically during a revolution of the rotor (4) onto the inertial measurement device (5), on the basis of the rotation of the earth that acts cyclically during a revolution of the rotor (4) onto the inertial measurement device (5), and/or on the basis of a rotary encoder of the rotor (4).
12. Method according to any one of claims 9 to 11, wherein

    - the structure comprises at least a part of a wind turbine (1) having a rotor (4), and wherein the inertial measurement device (5) is arranged on the rotor (4), comprising

    - detecting an imbalance of the rotor (4) on the basis of the detected rotation rates and acceleration values.

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